UPDATED 9/27/06 with additional plug numbers.
UPDATED 10/14/05 with additional plug numbers.
Just thought I'd post up what works and what doesn't for my '98 AEB engine.
And by triple-electrode, I'm talking about the OEM-style copper-electrode plugs, not platinum. I experimented with the Bosch Platinum Single-Electrode F5DPOR, and it met my heat-range needs, but power dropped off radically after 6000 rpm. The FR5DTC's gave me the heat range I needed w/o killing power at high RPM.
I have run the following triple-electrode (copper) plugs in my car, all with great success:
Bosch FR5DTC (best) [two heat ranges colder than OEM]
Bosch F6DTC (next-best) [one heat range colder than OEM]
Denso K22PBR-S (next-best) [one heat range colder than OEM]
Bosch F7LTCR (OEM plug) (too hot for high boost) [OEM heat range]NOTE: 5/28/07 this plug has been replaced by the two-electrode FR7LDC+. Go figure. They seem to work.
Denso K20PBR-S10 (too hot for high boost) [OEM heat range]
NGK BCP6ET (too hot for high boost) [OEM heat range]
Here's some more triple-electrode plug numbers, but I haven't tried them:
NGK BCP7ET [one range colder than OEM]
NGK BKUR6ET [OEM heat range]
NGK BKUR7ET [one range colder than OEM]
The following single-electrode plugs haven't worked well at all.
Autolite - forgot the number
NGK PFR7Q [one range colder than OEM]
The single-electrode plugs misfire. They just do. I've even got VAG-COM error codes to prove it. Especially this last, brand-new batch of NGK PFR7Q's. They misfired BAD when cold. OK when warm, but the engine didn't feel as strong. After three days, I put my used Densos back in, and the car ran great. The PFR7Q's were sooty as hell on the electrode, but the insulator was white as a sheet.
Recall that the AEB has larger intake valves than the subsequent engine codes. Looking at the plugs side-by-side, they extend the same depth into the combustion chamber. But the three-electrode design puts the spark about 1/8" further into the chamber. I think, for the AEB anyway, that this must be necessary. Plus, with the triple-electrode design, the flame front has clear propagation into any part of the combustion chamber. The single-electrode design prevents the flame from propagating evenly on the electrode side. Again, this may be a critical design parameter only for the flow characteristics of the AEB head.
Single-electrode plugs (PFR6Q) are OEM for the ATW, AUG, and AWM engine codes. So if they are working fine for you, don't switch.
For the members that are successfully using singles in your AEB - admittedly, my engine asks more from a plug than a stock engine or even a chipped one. I have port-matched the intake manifold and ports, and port-matched the exhaust mani, and a few other things. And I "suffer" from radically advanced timing due to my "Holey MAF" mod. So you can see that my combustion chamber would put more "stress" on the spark. But I think by extension, if you have an AEB, you'd get better performance using triples. If you need cheap triples, get the Densos.